// This file was taken from https://github.com/mrdoob/three.js/blob/dev/examples/js/loaders/DDSLoader.js
import {
  CompressedTextureLoader,
  RGBAFormat,
  RGB_S3TC_DXT1_Format,
  RGBA_S3TC_DXT3_Format,
  RGBA_S3TC_DXT5_Format,
  RGB_ETC1_Format,
  CompressedPixelFormat
} from 'three';

class DDSLoader extends CompressedTextureLoader {

  constructor( manager ) {
    super( manager );
  }

  parse(buffer, loadMipmaps) {
    const dds = {
      isCubemap: false,
      mipmaps: [],
      width: 0,
      height: 0,
      format: null,
      mipmapCount: 1
    };
    // Adapted from @toji's DDS utils
    // https://github.com/toji/webgl-texture-utils/blob/master/texture-util/dds.js
    // All values and structures referenced from:
    // http://msdn.microsoft.com/en-us/library/bb943991.aspx/

    const DDS_MAGIC = 0x20534444; // const DDSD_CAPS = 0x1;
    // const DDSD_HEIGHT = 0x2;
    // const DDSD_WIDTH = 0x4;
    // const DDSD_PITCH = 0x8;
    // const DDSD_PIXELFORMAT = 0x1000;

    const DDSD_MIPMAPCOUNT = 0x20000; // const DDSD_LINEARSIZE = 0x80000;
    // const DDSD_DEPTH = 0x800000;
    // const DDSCAPS_COMPLEX = 0x8;
    // const DDSCAPS_MIPMAP = 0x400000;
    // const DDSCAPS_TEXTURE = 0x1000;

    const DDSCAPS2_CUBEMAP = 0x200;
    const DDSCAPS2_CUBEMAP_POSITIVEX = 0x400;
    const DDSCAPS2_CUBEMAP_NEGATIVEX = 0x800;
    const DDSCAPS2_CUBEMAP_POSITIVEY = 0x1000;
    const DDSCAPS2_CUBEMAP_NEGATIVEY = 0x2000;
    const DDSCAPS2_CUBEMAP_POSITIVEZ = 0x4000;
    const DDSCAPS2_CUBEMAP_NEGATIVEZ = 0x8000; // const DDSCAPS2_VOLUME = 0x200000;
    // const DDPF_ALPHAPIXELS = 0x1;
    // const DDPF_ALPHA = 0x2;
    // const DDPF_FOURCC = 0x4;
    // const DDPF_RGB = 0x40;
    // const DDPF_YUV = 0x200;
    // const DDPF_LUMINANCE = 0x20000;

    function uint8ArraytoInt32( value, offset ) {
      return value[offset] + (value[offset+1] << 8) + (value[offset+2] << 16) + (value[offset+3] << 24);
    }

    function fourCCToInt32( value ) {

      return value.charCodeAt( 0 ) + ( value.charCodeAt( 1 ) << 8 ) + ( value.charCodeAt( 2 ) << 16 ) + ( value.charCodeAt( 3 ) << 24 );

    }

    function int32ToFourCC( value ) {

      return String.fromCharCode( value & 0xff, value >> 8 & 0xff, value >> 16 & 0xff, value >> 24 & 0xff );

    }

    function loadARGBMip( buffer, dataOffset, width, height ) {

      const dataLength = width * height * 4;
      const srcBuffer = new Uint8Array( buffer, dataOffset, dataLength );
      const byteArray = new Uint8Array( dataLength );
      let dst = 0;
      let src = 0;

      for ( let y = 0; y < height; y ++ ) {

        for ( let x = 0; x < width; x ++ ) {

          const b = srcBuffer[ src ];
          src ++;
          const g = srcBuffer[ src ];
          src ++;
          const r = srcBuffer[ src ];
          src ++;
          const a = srcBuffer[ src ];
          src ++;
          byteArray[ dst ] = r;
          dst ++; //r

          byteArray[ dst ] = g;
          dst ++; //g

          byteArray[ dst ] = b;
          dst ++; //b

          byteArray[ dst ] = a;
          dst ++; //a

        }

      }

      return byteArray;

    }

    const FOURCC_DXT1 = fourCCToInt32( 'DXT1' );
    const FOURCC_DXT3 = fourCCToInt32( 'DXT3' );
    const FOURCC_DXT5 = fourCCToInt32( 'DXT5' );
    const FOURCC_ETC1 = fourCCToInt32( 'ETC1' );
    const headerLengthInt = 31; // The header length in 32 bit ints
    // Offsets into the header array

    const off_magic = 0;
    const off_size = 1;
    const off_flags = 2;
    const off_height = 3;
    const off_width = 4;
    const off_mipmapCount = 7; // const off_pfFlags = 20;

    const off_pfFourCC = 21;
    const off_RGBBitCount = 22;
    const off_RBitMask = 23;
    const off_GBitMask = 24;
    const off_BBitMask = 25;
    const off_ABitMask = 26; // const off_caps = 27;

    const off_caps2 = 28; // const off_caps3 = 29;
    // const off_caps4 = 30;
    // Parse header

    const header = new Int32Array( buffer, 0, headerLengthInt );

    if ( header[ off_magic ] !== DDS_MAGIC ) {

      console.error( 'THREE.DDSLoader.parse: Invalid magic number in DDS header.' );
      return dds;

    }

    let blockBytes;
    const fourCC = header[ off_pfFourCC ];
    let isRGBAUncompressed = false;

    switch ( fourCC ) {

      case FOURCC_DXT1:
        blockBytes = 8;
        dds.format = RGB_S3TC_DXT1_Format;
        break;

      case FOURCC_DXT3:
        blockBytes = 16;
        dds.format = RGBA_S3TC_DXT3_Format;
        break;

      case FOURCC_DXT5:
        blockBytes = 16;
        dds.format = RGBA_S3TC_DXT5_Format;
        break;

      case FOURCC_ETC1:
        blockBytes = 8;
        dds.format = RGB_ETC1_Format;
        break;

      default:
        if ( header[ off_RGBBitCount ] === 32 && header[ off_RBitMask ] & 0xff0000 && header[ off_GBitMask ] & 0xff00 && header[ off_BBitMask ] & 0xff && header[ off_ABitMask ] & 0xff000000 ) {

          isRGBAUncompressed = true;
          blockBytes = 64;
          dds.format = RGBAFormat;

        } else {

          console.error( 'THREE.DDSLoader.parse: Unsupported FourCC code ', int32ToFourCC( fourCC ) );
          return dds;

        }

    }

    dds.mipmapCount = 1;

    if ( header[ off_flags ] & DDSD_MIPMAPCOUNT && loadMipmaps !== false ) {

      dds.mipmapCount = Math.max( 1, header[ off_mipmapCount ] );

    }

    const caps2 = header[ off_caps2 ];
    dds.isCubemap = caps2 & DDSCAPS2_CUBEMAP ? true : false;

    if ( dds.isCubemap && ( ! ( caps2 & DDSCAPS2_CUBEMAP_POSITIVEX ) || ! ( caps2 & DDSCAPS2_CUBEMAP_NEGATIVEX ) || ! ( caps2 & DDSCAPS2_CUBEMAP_POSITIVEY ) || ! ( caps2 & DDSCAPS2_CUBEMAP_NEGATIVEY ) || ! ( caps2 & DDSCAPS2_CUBEMAP_POSITIVEZ ) || ! ( caps2 & DDSCAPS2_CUBEMAP_NEGATIVEZ ) ) ) {

      console.error( 'THREE.DDSLoader.parse: Incomplete cubemap faces' );
      return dds;

    }

    dds.width = header[ off_width ];
    dds.height = header[ off_height ];
    let dataOffset = header[ off_size ] + 4; // Extract mipmaps buffers

    const faces = dds.isCubemap ? 6 : 1;

    for ( let face = 0; face < faces; face ++ ) {

      let width = dds.width;
      let height = dds.height;


      for ( let i = 0; i < dds.mipmapCount; i ++ ) {

        let byteArray, dataLength;

        if ( isRGBAUncompressed ) {

          byteArray = loadARGBMip( buffer, dataOffset, width, height );
          dataLength = byteArray.length;

        } else {

          dataLength = Math.max( 4, width ) / 4 * Math.max( 4, height ) / 4 * blockBytes;
          byteArray = new Uint8Array( buffer, dataOffset, dataLength );

        }

        const mipmap = {
          'data': byteArray,
          'width': width,
          'height': height
        };
        dds.mipmaps.push( mipmap );
        dataOffset += dataLength;
        width = Math.max( width >> 1, 1 );
        height = Math.max( height >> 1, 1 );
      }
    }

    return dds;
  }
}
export { DDSLoader };
